New Defender's Study Bible Notes
4:11 head of the corner. Peter, with John, preached with great boldness, even accusing the same chief priests that had manipulated the crucifixion of Jesus just a few weeks before. That same Peter had once been so fearful of his life that he denied Christ three times. The amazing transformation in Peter can only be explained in one way: he knew beyond any question that Jesus had triumphed over death and was now energizing him by His indwelling Spirit. He quoted Psalm 118:22 to them, exactly as Jesus had done earlier (Matthew 21:23,42), applying it directly against them.
4:12 none other name. This is one of the clearest statements that can be found anywhere setting forth the one way of salvation. Only Christ can save, for He both created and sustains all things. He Himself has made this plain (e.g., John 14:6). As offensive as such a truth may be to non-Christians, we must continually make it clear in our witness to them, for without Christ they are lost and bound for hell.